JPS589879A - Manufacture of anisotropic carbon formed body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing carbon shaped bodies without additional binders.

Such carbon compacts are used industrially as anodes for chlor-alkali electrolysis, anode blocks for aluminum (lamb production), electrodes for arc furnaces for steelmaking, and for construction of machinery, equipment structures, and the electronics industry.
Used as a component.

The quality characteristics of carbon molded bodies are true density, apparent density, strength, heat resistance, electrical conductivity, thermal expansion, porosity, black structure, trace element content, and emphasis differs depending on the purpose of use. Such compacts are manufactured by mixing, forming and sintering from coke and a binder using conventional techniques.The coke is generally calcined petroleum coke or partially calcined nine-pitch coke. Point 10
0'c petroleum pitch and coal tar pitch are used.

In order to obtain a high density, the molded product may be 3 Ut” depending on the purpose of use.
It must be impregnated and finished fired before being processed to its final size. ◎ The literature also describes a method for manufacturing acid-expanded forms without the addition of a binder. According to the above, a carbonizable material with a volatile content of 8 to 1 o is recommended as a preliminary step to the production of a molded body. Carbonizable materials with this level of residual volatile content are typically green coke produced at temperatures near 500'C.

The raw coke is cold-milled and then heated to a suitable temperature range, particularly 350-450'C and 10/min.
compressed under pressure of 1.

Temperature exceeding 1000℃ after mold removal 1 Carbonization occurs O 300-500℃ and 600℃ generates a large amount of gas
In the range from 800 DEG C. to 800 DEG C., the ninth smallest temperature gradient must be chosen to avoid the formation of cracks in the compact. 2500-3000'C where coke turns into graphite.

After graphitization, the compact is in the most preferred case 26-
It has a porosity of ◎The density of this porous molded body is K
ll! It is a quality feature.

A similar method for producing molded bodies based on pitch extract is described in British Lil Patent Specification No. 1,416,573'. Mesophase (M@5ophase) content 9.6~2
5- Thermally pretreated pitch has a graphitizable phase and a non-graphitizable phase consisting of a mesophase (8 ph ro 11 t) dispersed in an organic solvent such as quinoline, pyridine or tar oil. The intermediate phase is separated into a pitch phase with a diameter of 1 to 100 μvn14 → and is covered by an isotropic pitch of about 10 − By thorough separation of the pitch, a powdered coke material is obtained after carbonization. The material can be further processed into quasi-isotropic molded bodies with a suitable binder. Pitch content - If high, the molded body can be produced without additional binder or with residual pitch. To serve this purpose, it is directly possible to achieve a density of 1.3.
4-1. '12117dt''? Yes.

The two methods just described require expensive pretreatment steps for the materials used, making it impractical to economically implement mass production methods.
A simple method for producing carbon compacts made of pitch-like hydrocarbon materials without the use of additional binders is described in the Japanese magazine "Carbon", 1968, Rattan 52l1, pages 13-17. .

According to this, a modified hard pitch with a softening point exceeding 170°C is mixed with a water-ethyl alcohol mixture of 6 to 6 times the amount.
The sludge is crushed and mixed into a sludge in the runle and then poured into the ceracola that previously produced it by the same method known from the pottery industry.The water is absorbed by the sludge and is poured into the sludge by the same method known from the pottery industry. A layer with a maximum thickness of 6 mm consisting of finely dispersed pitch of I11 peels off from the base. Is it possible to compress this before stabilizing the formed body? The stabilization line of the "green" pitch compact thereby increases the density of the final coke compact and reduces its porosity, for example by making it unmeltable at temperatures close to the softening point in an ozone atmosphere. It will be done. Subsequent carbonization 4
Porosity of 150-9016 and 1.45-0.75&
A molded body having a molded body density of /C1l is obtained.

In this method as well, a low temperature rise is desired during the sintering of the individual particles to avoid deformation of the compact due to the high degassing rate. The microstructural line, isotropy, and other physical properties of the round-bottomed shape are very closely related to the modified hard pitch production method, such as distillation or air blowing.

Objective of the present invention: To easily produce large-sized anisotropic carbon compacts directly from high-boiling aromatic hydrocarbon fractions with high carbonization residues derived from coal or mineral oil sources, avoiding intermediate steps and without using high pressure. That's 7f! be.

The purpose of the present invention is to grind a hydrocarbon fraction having a softening point exceeding 40'C (Kramer-Dernault method KB) to a liquid state, fill it into a gourd in a round shape, and complete the dropping step 1. Up to 550' until converted to raw coke
CK heating, and then in the second step 1, the molded body was heated directly @(1(+
a) Heating linearly at a heating rate of 1 to 2 K/day depending on K at about aoo"ct, and the molded body thus produced is impregnated with a pitch of 11 to several times in some cases, and then heated to a minimum of 850 °C. Solved by firing, layering, and graphitizing.

In particular, a hydrocarbon fraction with a content of medium/insoluble components of less than 1 is used as a raw material, and when treating coal tar, Ti is obtained as a distillation residue when treating high-boiling aromatic residues from steam cracking of a mineral oil fraction. It will be done. In particular, hard pitches with a softening point (K8) above 100° C. are used.

A shrinkage factor of 5- has to be taken into account to ensure the dimensional stability of the molded body. The first heating step includes two stages. 1st
R"?'Deeply filled hard pitch interphase formation open#
! It will be heated.

During further heating in the subsequent second stage 7, an anisotropically deformable liquid crystal, a so-called mesophase, is generated from the isotropic pitch melt due to the rounding of intermolecular forces. During the subsequent rapid temperature rise, the interphase a solidifies into raw coke.During carbonization from the interphase to raw coke, separation products are generated as a result of the condensation reaction, and this product As bubbles escape through the anisotropic mesophase which then solidifies into stripes. The rising bubbles generate a shear stress at the phase boundary with the intermediate phase, and the ζ stress inevitably forms an acicular structure in the direction of the rising bubbles in the intermediate phase. This forming force increases the faster the heating and therefore the degassing. In the case of a cylindrical stand that stands upright, is the line of force in the axial direction? The highest strength values and the highest electrical conductivity are achieved in the orientation direction with a certain zero graphitization. Since the solidified mesophase has approximately the same orientation throughout the molded body, no internal stress occurs in the axial direction of the molded body when subjected to thermal loading.

If desired, impregnation can be carried out before the shaped body is removed from the disk. The impregnation is carried out according to the method of the invention in a number of steps, so that the impregnation pitch is particularly high for porous coke compacts solidified indoors.
The preferred temperature range for filling and impregnation is, for example, 300-370° C.1, depending on the impregnation pitch used, after the temperature has initially fallen to 300-420° C. The impregnated pitch penetrates into the capillary system formed by the pores formed during the initial carbonization due to gravity. According to the method of the present invention, the coke molded product is heated to a temperature at which it shrinks. Shrinkage reaches a maximum at about 800°C; therefore this temperature must be controlled very carefully so that the shrinkage stress that occurs does not rise above the maximum tension. If the heating is carried out too quickly, radial cracks will occur that will prevent the compact from being used as an electrode.In order to produce the carbon compact according to the present invention, a heating curve consisting of two parts as described above is required. - The first part of the heating curve reaches about 660 °C (first stage and second stage) 1 Green coke formation is completed. The heating curve is T = a-yn (T is temperature °C, In the case, the shear a or n is mainly due to the difference in raw materials. 50<a
<150 especially 80-1000.30<n<0.7
0 is particularly advantageous in the range of 0.5 to 0.6. Heating curves that differ from this are also possible. However, if the heating is too early, the porosity of the molded body becomes undesirably large, and if the heating is too slow, no obvious crystal alignment occurs.

The second part of the heating curve is f! F! It passes in a straight line.

The rise in heating temperature IIIA depends only on the diameter of the compact and has the following magnitude: 6-Q,l @ -+ Fmi 120 °C/dd-0,21
1L-41≧ 50℃/dd=0.4 lectures → I2: 8℃
/d 6 = Q, 8 m → #ζ 2 °C / d The discontinuity that occurs between the two heating curves is advantageously smoothed out by the transition curve 0 From the required heating rate the production time is obtained, and then If the dimensions of the expanded molded body are large, the dimensions of the molded body with the same degree of expansion as in the conventional method are small.

The method of the invention allows short baking times.

Next, the present invention will be explained by way of an example. Example 1: A cylindrical metal container with a diameter of 120 saws and a smooth inner surface is filled with pitch having the following characteristic values obtained by distillation from the pyrolysis residue of crude benzene vapor decomposition. : mp(Is): 120°C QI: 0.31G 'I'l: 22- Ash content: - There is one step after heating: 20-660°C for 18 hours Axial acicular structure of mesophase crystals occurs. The carbonization period is 560~630°C for 20 hours and 630~830°C for 60 hours.The shrinkage rate is 511''I!1.

Cooling: 26 hours 110 hours 1 A crack-free coke molded body is generated that can be taken out by simply overturning the plate. The carbon yield is 8811"1'. The porosity is 32-1. The axial needle-like structure is 1.

Coke compacts can be graphitized using conventional methods. The abbreviations IF ([8) represent the softening point (Kramer-Zarnow method), QI shows the solubility of minerals, and TI represents the insolubility of toluene. Example 2: Hard pitch distilled from coal tar pitch separated into metal solder with a diameter of 400 mm. (1! P160℃).

The heating curve is as follows: 20-650°C 18 hours = - The compact has a porosity of 36 after heat treatment 550-400'C 10 hours Cooling 400°C 6 hours Distilled hard pitch (EP 160°C) The porosity of the compact is reduced by adding to the degassed top surface.

400-550℃ 10 hours Added and nine impregnated pitch carbonized, showing the same axial crystal structure as the primary carbonized material @ 660-630℃ 60 hours 630-830℃ 360 hours 830-20℃ 100 hours 554 hours Tipping A crack-free coke molded body with a diameter of 375 cm, which can be opened indoors, is produced.

The porosity of the fired compact is 161G-? be.

The shaped bodies can be graphitized in a conventional manner.

Example 3 = A 630 m diameter cylindrical metal bed is filled with filtered coal tar standard pitch and residual oil from ethylene pyrolysis in a ratio of 1=1 (BP approx. 40°C) 0 heating curve Hiroji's Toshi : 20-630℃ 24 hours 630-360℃ 16 hours 360℃ 10 hours Filtered coal tar standard pitch (I
1st impregnation with filtered coal tar standard pitch 360°C 10 hours 360-530°C 18 hours 630-630°C 120 hours 630-830°C 1900 11,600 pieces of coke molded body are generated in 200 hours and 2327 hours at 830 to 20°C.

The porosity is 13s''e〇 The molded body is graphitized by the conventional method ◎ The following table shows the advantages of the method of the invention over the conventional method in Example 1 of electrode production 〇 Method comparison Conventional method Method of the invention

Claims (1)

[Claims] 1. Producing anisotropic carbon compacts from a high-boiling aromatic hydrocarbon fraction with a high carbonized residue obtained from coal or expanded mineral oil without the use of additional binders and high pressure. In the method, a expanded hydrogen fraction with a softening point exceeding 40°C (Kramer-Zarnault method) is ground in a liquid state and filled into a plate, and heated until it is completely converted into raw coke. ^ Heated to 660°C, then linearly heated in the second stage to 800°C at a heating rate of 1.2 djlk/oty, which depends on the diameter d (s*) of the compact. A method for producing an anisotropic carbon compact characterized by firing the compact at a minimum of 850°C and forming a layer liquid. The manufacturing method according to claim 1 which uses the boiling point aromatic pyrolysis residue during steam decomposition & the distillation residue has a softening point of over 100°C (clay i-zu Renault process) and has a The manufacturing method according to claim 2, which contains a Norin-insoluble component of less than 1%. Ob S number T=a・i
Heating white line by n [T represents temperature °C, τ company time,
Heating according to the constant aa of 50 to 150 and the index n of 0 within the range of 0.3 to 0.7.
A method according to one of clauses 6. 6. The molded body has a softening point of 300-420℃ (Kramer,
(Zarnow method) Impregnating with pitch at 120 to 170°C, heating at that time, flowing good liquid pitch to the opening on the shoe, and penetrating into the molded body only by the action of gravity.Claim 1
Manufacturing method 0 according to one of items 6 to 6